Effect of Neutrophil Priming on Chemotaxis and Signaling

中性粒细胞启动对趋化性和信号传导的影响

• 批准号: 6739082
• 负责人: Jonathan S Reichner
• 金额: $ 21.12万
• 依托单位: RHODE ISLAND HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-05-01 至 2007-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6739082
• 关键词: biological signal transduction; candidiasis; cell membrane; cell migration; chemotaxis; clinical research; confocal scanning microscopy; glucans; glycosylphosphatidylinositols; host organism interaction; human subject; immunofluorescence technique; immunoprecipitation; integrins; laboratory rat; leukocyte activation /transformation; leukocyte adhesion molecules; mitogen activated protein kinase; molecular shape; neutrophil; phosphorylation; receptor binding; septicemia; western blottings

DESCRIPTION (provided by applicant): Polymorphonuclear leukocytes (PMN) are an inherently motile cell type, which can be directed to move up a chemoattractant gradient. Chemotactic movement is essential for PMN accumulation at sites of tissue injury or infection, however, mechanisms which provide the navigational signals needed to give direction to these cells are incompletely understood. Candida albicans is the fourth leading cause of nosocomial infections with post-surgical, trauma and immunosuppressed patients being at highest risk. Beta-glucan, a major component of the yeast cell wall, is elaborated into the bloodstream of patients with systemic candidiasis although the role of beta-glucan in the pathobiology of the disease is not clear. Recent findings from this laboratory have shown beta-glucan, converts PMN migration from random to direct. The conversion is mediated by recognition of beta-glucan by the leukocyte beta2integrin CR3 (CD11 b/CD18) and is a previously unrecognized effect of beta-glucan on neutrophil function. The long-term goal of our work is to understand how host defenses are affected by beta-glucan during the course of systemic fungal infections. The focus of the current proposal is to determine the mechanisms through which beta-glucan recognition by CR3 alters neutrophil function. Experiments in Aim I will investigate the role of several intracellular signaling pathways that, based on our current findings, are hypothesized to mediate the increased chemotactic capacity of neutrophils migrating on beta-glucan supplemented matrix. Specific Aim II will apply a well-characterized wound model to demonstrate the effect of beta-glucan on the ability of the host neutrophils to respond to injury. In vitro findings have determined that activation of CR3 by beta-glucan regulates the function of integrins of the beta1 family. The wound model will determine whether beta-glucan and/or systemic candidiasis similarly alters the function of beta1 integrins in mediating PMN entry into a site of injury. Finally, several proinflammatory mediators (LPS, immune complexes, urokinase plasminogen activator) bind to glycosylphosphatidylinositol (GPI)-Iinked receptors (CD14, CD16, CD87), which in turn rely on CR3 for intracellular signaling. Specific Aim III will test the hypothesis that a novel pathway of beta1 integrin crosstalk dissociates GPl-linked receptors from CR3 molecules. Since beta-glucan and GPl-linked receptors share a common CR3 binding site, dissociation of GPl-linked receptor from CR3 would simultaneously increase the number of CR3 molecules available for beta-glucan binding and blunt the response to ligands specific for GPl-linked receptors. The proposed studies will further elucidate the mechanism of action through which beta-glucan primes neutrophils both as a component of systemic fungal infections and as a biological response modifier with therapeutic potential for treating polymicrobial sepsis.

描述（由申请人提供）： 多形核白细胞 (PMN) 是一种本质上能运动的细胞类型，可以引导其沿着趋化剂梯度向上移动。趋化运动对于中性粒细胞在组织损伤或感染部位的积累至关重要，然而，为这些细胞提供方向所需的导航信号的机制尚不完全清楚。白色念珠菌是医院感染的第四大原因，术后、创伤和免疫抑制患者的风险最高。 β-葡聚糖是酵母细胞壁的主要成分，虽然β-葡聚糖在该疾病病理学中的作用尚不清楚，但它会进入系统性念珠菌病患者的血流中。该实验室的最新研究结果表明，β-葡聚糖可将 PMN 迁移从随机迁移转变为直接迁移。这种转化是通过白细胞 β2 整合素 CR3 (CD11 b/CD18) 对 β-葡聚糖的识别介导的，并且是 β-葡聚糖对中性粒细胞功能的先前未被认识的影响。我们工作的长期目标是了解在全身真菌感染过程中宿主防御如何受到 β-葡聚糖的影响。当前提案的重点是确定 CR3 识别 β-葡聚糖改变中性粒细胞功能的机制。目标 I 中的实验将研究几种细胞内信号传导途径的作用，根据我们目前的发现，这些信号传导途径被假设可介导中性粒细胞在补充 β-葡聚糖的基质上迁移的趋化能力增加。具体目标 II 将应用一个充分表征的伤口模型来证明 β-葡聚糖对宿主中性粒细胞响应损伤的能力的影响。体外研究结果表明，β-葡聚糖激活 CR3 可调节 β1 家族整合素的功能。伤口模型将确定 β-葡聚糖和/或系统性念珠菌病是否会类似地改变 β1 整合素介导 PMN 进入损伤部位的功能。最后，几种促炎介质（LPS、免疫复合物、尿激酶纤溶酶原激活剂）与糖基磷脂酰肌醇 (GPI) 相关受体（CD14、CD16、CD87）结合，而这些受体又依赖于 CR3 进行细胞内信号传导。具体目标III将测试以下假设：β1整联蛋白串扰的新途径将GP1连接的受体与CR3分子分离。由于β-葡聚糖和GP1连接的受体共享共同的CR3结合位点，因此GP1连接的受体从CR3解离将同时增加可用于β-葡聚糖结合的CR3分子的数量并减弱对GP1连接的受体特异的配体的反应。拟议的研究将进一步阐明β-葡聚糖启动中性粒细胞的作用机制，既作为全身真菌感染的组成部分，又作为具有治疗多种微生物败血症的治疗潜力的生物反应调节剂。